In order to meet wireless data traffic demands that have increased after 4th Generation (4G) communication system commercialization, efforts to develop an improved 5G communication system or a pre-5G communication system have been made. For this reason, the 5G communication system or the pre-5G communication system is called a beyond 4G network communication system or a post LTE system.
In order to achieve a high data transmission rate, an implementation of the 5G communication system in an mmWave band (for example, 60 GHz band) is being considered. In the 5G communication system, technologies such as beamforming, massive Multi-Input Multi-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large scale antenna are discussed to mitigate a propagation path loss in the mmWave band and increase propagation transmission distance.
Further, the 5G communication system has developed technologies such as an evolved small cell, an advanced small cell, a cloud Radio Access Network (RAN), an ultra-dense network, Device to Device communication (D2D), a wireless backhaul, a moving network, cooperative communication, Coordinated Multi-Points (CoMP), and received interference cancellation to improve the system network.
In addition, the 5G system has developed Advanced Coding Modulation (ACM) schemes such as Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), Non Orthogonal Multiple Access (NOMA), and Sparse Code Multiple Access (SCMA).
In a wireless communication system supporting a millimeter wave (mm Wave) band, it can be expected that a significant increase in communication capacity by using beam forming over a wide frequency band. A multi-antenna system in the mmWave band has a small antenna space due to a high frequency band, and accordingly, through a sharp beam obtained by using a plurality of antenna elements, a high beam forming gain can be acquired.
On the other hand, in the mmWave band, a Hybrid Beam Forming (H-BF) system that uses RF chains, in which the number of RF chains is less than the number of antenna elements, and a Full Digital beam-forming (FD-BF) system that uses the RF chains, in which the number of RF chains is the same as the number of antenna elements, are being considered as next-generation communication technologies. When many RF chains are used, a performance gain can be obtained through a diversity gain or a multiplexing gain, but the problems of cost, complexity and the like can generated.
In order to perform beam forming in the above two systems in the mmWave band, channel estimation and terminal feedback are required. In a conventional Long Term Evolution (LTE) system, for a Frequency Division Duplexing (FDD) method, in order to notify of channel information to base station, a terminal generates channel information by estimating a channel between the base station and the terminal, using a reference signal transmitted from the base station, and performs feedback of the same to the base station. A Precoding Matrix Indicator (PMI) and a Channel Quality Indicator (CQI) are representative examples of the feedback information. The PMI is information used by the base station to generate a precoding matrix and the CQI is information used by the base station to perform scheduling, and Modulation, and Coding Scheme (MCS) selection.
However, since a high path loss occurs in the mmWave band, it is difficult to use a channel estimation method using a reference signal, used in the conventional LTE, due to limitation in the coverage of the reference signal.